Hilgard Philip, Treichel Ulrich, Dries Volker, Dienes Hans Peter, Gerken Guido
Department of Gastroenterology and Hepatology, University Hospital Essen, Essen, Germany.
Hepatogastroenterology. 2005 Sep-Oct;52(65):1534-40.
The mechanisms of binding and uptake of hepatitis C-virus (HCV) are critical determinants of the infection-reinfection cycle but due to ongoing absence of a robust cell culture system, these mechanisms are still largely hypothetical. Cryoglobulins are atypical immunoglobulins, present in 40% of HCV patients. The aim of this study was to determine the role of these HCV-containing cryoglobulins as carrier molecules for viral uptake into primary human hepatocytes.
Cryoglobulins were precipitated from serum of chronically HCV-infected patients, labeled with biotin and incubated with freshly prepared hepatocytes from human liver tissue. Binding and endocytosis of HCV-cryoglobulins were studied by specific assays, ligand blot analysis and electron microscopy on hepatocellar plasma membranes.
Biotinylated HCV-cryoglobulins specifically bound to hepatocytes and inhibitors of homotypic endosomal fusion reduced their uptake and intracellular trafficking, Ligand-blot and electron microscopy analysis revealed adhesion to hepatocellular plasma membranes. Inoculation of human hepatocytes with HCV-cryoglobulins but not serum from the same patients induced HCV infection in vitro.
HCV may enter hepatocytes in conjunction with cryoglobulins via immunoglobulin or related receptors. We hypothesize, that this mechanism plays a role in chronic hepatitis to support the infection-reinfection cycle of the virus.
丙型肝炎病毒（HCV）的结合与摄取机制是感染-再感染循环的关键决定因素，但由于目前仍缺乏完善的细胞培养系统，这些机制在很大程度上仍属推测。冷球蛋白是一种非典型免疫球蛋白，存在于40%的HCV患者中。本研究的目的是确定这些含HCV的冷球蛋白作为病毒摄取进入原代人肝细胞的载体分子的作用。
从慢性HCV感染患者的血清中沉淀冷球蛋白，用生物素标记，并与新鲜制备的人肝组织肝细胞孵育。通过特异性检测、配体印迹分析和肝细胞质膜的电子显微镜研究HCV-冷球蛋白的结合和内吞作用。
生物素化的HCV-冷球蛋白特异性结合肝细胞，同型内体融合抑制剂减少其摄取和细胞内运输，配体印迹和电子显微镜分析显示其粘附于肝细胞质膜。用HCV-冷球蛋白而非同一患者的血清接种人肝细胞可在体外诱导HCV感染。
HCV可能通过免疫球蛋白或相关受体与冷球蛋白一起进入肝细胞。我们推测，这种机制在慢性肝炎中起作用，以支持病毒的感染-再感染循环。
